Power supplies for telecommunications equipment such as wireless base stations, etc., are required to deliver a regulated DC voltage such as 48 volts. These power supplies are powered by the AC line voltage, which voltage is rectified by known means such as a bridge rectifier. Power factor correction circuits are frequently used in power supplies of this type as is known. A power factor correction circuit causes the average current drawn from the AC input supply to be approximately in phase with the input voltage and to be a sinusoidal wave. This results in a more efficient operation with power factors approaching 0.99 being achievable.
One implementation of a power factor control circuit employs a boost converter comprising an inductor, a capacitor, and a controllable switch. The switch, such as a MOSFET, is controlled by a pulse width modulated (PWM) signal. The inductor and capacitor operate with the switch to alternatively store and discharge energy. One example of a power factor correction circuitry with a boost converter is described in U.S. Pat. No. 5,515,261 which issued May 7, 1996 to Bogdan. Other examples of boost converter circuits may be found in U.S. Pat. No. 5,550,458 which issued Aug. 27, 1996 to Farrington et. al. and U.S. Pat. No. 5,408,403 which issued Apr. 18, 1995. A circuit employing a snubber to minimize switching losses is described in U.S. Pat. No. 5,260,607 which issued Nov. 9, 1993 to Kinbara.